Haemoglobinopathies (HbP) are severe autosomal recessive disorders with high prevalence among certain ethnic groups. World Health Organisation (WHO) advises implementing screening programmes for risk groups. Research in the Netherlands has shown that general practitioners and midwives do not perceive ethnicity as a risk factor for HbP. Moreover, registration of ethnicity is a controversial societal issue, which may complicate the introduction of a national preconception or antenatal carrier screening programme. This study investigates attitudes, intention and behaviour of general practitioners and midwives towards ethnicity-based HbP-carrier screening in general. A structured questionnaire based on the Theory of Planned Behaviour was sent by mail to a random selection of 2100 general practitioners and 1800 primary care midwives. Response was 35% (midwives 44.2% GPs 27.6%). Although 45% of respondents thought that offering a carrier test on the basis of ethnicity alone should become national policy, it is currently not carried out. The main factor explaining lack of intention towards ethnicity-based HbP-carrier screening was subjective norm, the perception that their peers do not think they should offer screening (52.2% variance explained). If ethnicity-based HbP-carrier screening would become national policy, most professionals report that they would carry this out. Most respondents favoured ethnicity registration for health purposes. As most practitioners look for role models among peers, debate among general practitioners and midwives should be encouraged when new policy is to be developed, articulating the voices of colleagues who already actively offer HbP-carrier screening. Moreover, primary care professionals and professional organisations need support of policy at national level.